This proposal, in response to the RFA EB-03-006, addresses the development of low cost, portable, high quality ultrasound imagers. The proposed development takes advantage of the following on-going technical trends: 1. Development of micromachined ultrasound transducers (MUTs or cMUTs) to the stage where they are now viable candidates for ultrasound systems. 2. Development of the concept of reconfigurable arraysmuse of a switching matrix to reconstruct or regroup cMUT cells to optimize image acquisition and to minimize beamformer channels. One grouping of elements, an annular array configuration, is particularly attractive from performance and processing channel points of view. 3. Development of high density interconnect capabilities such as through wafer vias and 3D interconnect. 4. Development of PC based back ends for ultrasound scanners capable of performing all the post-beamformer signal processing (e.g. Doppler processing) and scan conversion. With these technologies, and their further development and enhancement during this project, GE Global Research and Stanford University will validate the concept of reconfigurable arrays by demonstrating equivalent or superior image quality with respect to conventional high end systems. The goal is to achieve this with a dramatically reduced channel count and required physical volume and hence dramatically reduced cost. The specific aims of this proposal are: 1. Identify the clinical application and the performance specification needed to match or supercede existing instrumentation. Use this information to identify cMUT array characteristics. 2. Develop the cMUT array, transmit/receive ICs, switching matrix, interconnect technology, and control software required to interface this IC assembly to a conventional scanner. 3. Measure the beam characteristics generated by the resulting scanner and perform initial image quality assessment with an in-house clinical. Achievement of these specific aims are a key step towards full integration of the concept of reconfigurable arrays. Once integrated with the beamformer and a "wearable" PC, portability of ultrasound will have reached a new level. It is expected that the availability of medical ultrasound will reach greater fraction of the population than ever before. Further, concepts such as wireless imaging, patient monitoring, remote manipulation of the imaging plane and its observation become real.